Various methods and machines have been disclosed for automatically opening envelopes, either singly or in batches.
Mechanical envelope openers which slit or cut an edge or edges of the envelope are disclosed in the U.S. Pat. Nos. 2,992,629 and 3,116,718.
An apparatus which contacts the edge of an envelope with a heated rod to carbonize the envelope material and cause mechanical failure of the envelope material is disclosed in the U.S. Pat. No. 3,132,629.
More recently, methods and apparatus have been developed for treating the edges of envelopes with chemicals that degrade or deteriorate the envelope material. Examples of such methods and apparatus are disclosed in the U.S. Pat. Nos. 3,677,460, 3,871,573, 3, 816,213, 4,069,011, and 4,106,432.
In some of the above-disclosed methods, a first chemical is applied to the envelope edges and activated by the application of an additional developing chemical so as to deteriorate the envelope paper along the edges. Mild mechanical abrasive action may be employed to fully separate the treated edges. Some of these chemical methods are activated or assisted by the application of heat. For example, in the aforerentioned U.S. Pat. Nos. 3,816,213, 3,871,573, and 3,677,460, a process of heating the envelope edges by radiant means is disclosed. Similarly, U.S. Pat. Nos. 3,902,429, and 3,815,325 disclose methods of chemically deteriorating envelope edges wherein heat is applied to the chemically treated edges of the envelopes with forced warm air.
In other methods of opening envelopes by chemical deterioration of the envelope edges, heat is applied by direct contact with a heating member. Such a process is disclosed in the aforementioned U.S. Pat. No. 4,069,011 and also in the U.S. Pat. No. 4,082,603.
When automatically opening large numbers of envelopes arranged in batches by heat-assisted chemical deterioration of the envelope edges, it is desirable to provide a transfer of heat to the envelope edges. In general, it is desirable to raise the envelope edge temperature to a level where the amount and/or rate of chemical deterioration of the envelope material is significantly increased.
In those instances where it is desired to heat the envelope edges with a heating member to promote, assist, or activate the chemical deterioration of the envelope edges, it is desirable to provide good contact between each envelope edge and the heating member.
In processes disclosed in some of the above-discussed patents, a chemical solution is sprayed onto the envelope edges prior to the envelope being brought into contact with the heating member. It would be beneficial, once the sprayed chemical has sufficiently penetrated the envelope material along the envelope edges, to concentrate the chemical on the envelope, as by raising the temperature of the chemical and causing evaporation of some of the liquid, if any, in the chemical solution. If the temperature is raised sufficiently, the chemical deterioration of the paper will be effected at a greatly increased rate. Further, vapors that may be generated between the edges of adjacent envelopes should preferably be dissipated.
It would also be desirable to provide an apparatus for quickly and easily applying a controlled amount of a liquid spray of an envelope degrading chemical or chemicals to the edges of the envelopes in a manner that assures a uniform coverage of the liquid on each envelope edge to be opened.
It would also be advantageous to provide an apparatus for conveying batches of envelopes in a relatively compact path wherein one, two, or three edges of each envelope could be efficiently opened.
In a method for opening envelopes by chemical deterioration of the envelope edges, it would be desirable to ensure that the edges of the envelopes were properly aligned with the spray (and heat source if used) during the opening process to ensure that each of the envelopes in a given batch has substantially uniformly deteriorated edges.
With a chemical envelope opening process, it would also be desirable to provide a vapor filtration and recirculation system to eliminate undesirable gaseous releases to the atmosphere.
In a method for opening the edges of chemically treated envelopes, it would also be advantageous to provide means for mildly abrading the chemically degraded envelope edges to remove any particulate matter and to insure complete mechanical failure of the envelope edges.